Early On, Hormone Therapy May Raise Women's Heart Risks

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THURSDAY, Feb. 18, 2010 (HealthDay News) -- Hormone replacement therapy does not lower the odds of heart trouble in women who take the regimen to ease hot flashes and other symptoms of menopause, a new study reports.

In fact, the researchers say, it will probably elevate the risk for heart attacks for the first two years of use.

"There was no protective effect after women first started hormone therapy," said Dr. James Liu, chairman of obstetrics and gynecology at MacDonald Women's Hospital, University Hospitals in Cleveland, who was not involved with the study. "There may be some benefit later on, but it's subtle," he added.

The study reported that women who started taking hormone therapy within 10 years of menopause and who had been taking it for six years might derive some heart-protective effects, but the protection did not reach statistical significance.

No protection was found for women who started hormone therapy at least 10 years after menopause.

The findings, published in the Feb. 15 issue of Annals of Internal Medicine, do not change any current recommendations regarding the widely debated use of hormone therapy, the researchers said.

"If women are thinking about using hormone therapy for menopausal symptoms, they should use the lowest dose and for the shortest duration possible," said the study's lead author, Sengwee Darren Toh, an instructor in population medicine at Harvard Medical School in Boston. Toh worked at the Harvard School of Public Health when the study was conducted.

The findings stem from a new analysis of data from the Women's Health Initiative (WHI), a large, government-sponsored study. Earlier reports from the WHI showed an overall elevated risk for coronary heart disease among women taking estrogen-plus-progestin therapy, called combined hormone therapy.

However, much debate has circulated around whether the risk differs depending on when women start taking the therapy in relation to when they entered menopause.

The so-called "timing hypothesis" has postulated that heightened risk might not exist for women at the younger end of the spectrum.

Originally, the WHI data was analyzed according to the number of women assigned to each arm -- whether they were taking hormones or placebos -- and did not take into account people who stopped taking the therapy or who crossed over to another arm, Liu explained.

And about 40 percent of the 16,000-plus women participating in the part of the study examining hormone use did not take their assigned treatment, a proportion that increased over time.

"We need to account for this noncompliance if we want to estimate how the effects of hormone therapy on coronary heart disease change over time," Toh said.

In their analysis, Toh and his colleagues found that, overall, women who took combined hormone therapy for the first two years of the study had more than double the risk for heart attack and other coronary problems.

The increased risk was 69 percent among those taking hormone therapy for eight years.

Among women who started hormone therapy within a decade of menopause, the risk was raised just 29 percent, not considered statistically significant. Over the first eight years of use, the risk for heart attacks was 36 percent lower in this group, the study reported.

"Our paper suggests that both timing of initiating and time since initiation are important aspects to consider when we discuss the effects of hormone therapy on heart disease risk," Toh said.